Age Related Eye Disease and Alzheimer's Didn't Seem Linked

Age related macular degeneration and Alzheimers disease not linked in new study

(RxWiki News) While the chances of developing age-related macular degeneration or Alzheimer’s disease increase with age, older adults who develop one of these diseases are not necessarily at a greater risk of developing the other.

Age-related macular degeneration (AMD) is an eye condition that can lead to vision loss in older adults. Alzheimer’s disease is another condition that typically affects older adults and causes problems with memory and thinking.

A recent study found that AMD patients were not at an increased risk of developing Alzheimer’s disease or dementia. The researchers also found that Alzheimer's disease patients were not at an increased risk of developing AMD.

The researchers did note, however, that they may have come to these results because patients with one disease might be focused on that disease and less likely to notice symptoms of the other.

"Visit your primary care provider regularly for checkups."

This study was led by Tiarnan D. L. Keenan, MRCOphth, of the Centre for Hearing and Vision Research in the Institute of Human Development at the University of Manchester in England.

The research team examined whether people with AMD were more or less likely to develop Alzheimer’s disease in the following years. They also examined whether people with Alzheimer’s disease were more or less likely to develop AMD in the following years.

AMD typically occurs in people over the age of 50, and happens when the part of the eye that is used for central vision begins to break down. Alzheimer’s disease is a progressive brain disease that slowly destroys memory and thinking skills.

Data was analyzed from a total of 233,986 participants in the English National Health Service between 1999-2011. Of these participants, 65,894 had been diagnosed with AMD and 168,092 had been diagnosed with Alzheimer’s disease or dementia.

Patients were not eligible to be in the AMD group if they had been diagnosed with Alzheimer’s at the same time or before they were diagnosed with AMD. Similarly, patients were not eligible to be in the Alzheimer’s disease group if they had been diagnosed with AMD at the same time or before they were diagnosed with Alzheimer’s.

Several factors were taken into account when analyzing the findings. These factors included age, sex, region of residence, calendar year of admission and socioeconomic status.

The researchers found that for people with AMD, there was no significant increase in the risk for dementia. The rate ratio for developing Alzheimer’s was less than one (0.86). This means that AMD patients had a lower rate of Alzheimer's disease than people without AMD.

The rate ratio for developing dementia was also less than one (0.91). This again means that AMD patients had a lower rate of dementia than people without AMD.

The researchers also found a significant decrease in the likelihood of being admitted to the hospital for AMD among Alzheimer’s disease or dementia patients.

The researchers offered a few possible explanations for their findings. They noted that patients with dementia may be less likely to have regular eye appointments, less likely to notice or report vision problems and more dependent on caregivers to report any problems.

Additionally, the researchers noted that there may be issues with obtaining informed consent for eye exams from dementia patients.

The authors of this study concluded that based on their findings, the likelihood of having AMD and developing Alzheimer’s disease or of having Alzheimer’s disease and then developing AMD is no greater than what would happen by chance.

“Because there are similar pathologic features between AMD and [Alzheimer's disease], there has recently been speculation that the conditions may either be related or that either disease alone may be a risk factor of developing the other. Fortunately, this large study should help quell those fear," said Christopher Quinn, OD, optometrist at Omni Eye Services.

"It would appear that having either condition alone does not increase the risk of the developing the other. Either condition alone can be quite debilitating so patients can take comfort in the fact that having one of these conditions does not increase their risk of developing the other," said Dr. Quinn.

"Patients can reduce their risk of developing the most serious effects of AMD by stopping smoking, and many patients can benefit from proper nutrition. Making sure you get an annual comprehensive eye exam can identity AMD at its earliest stages," he said.

This study was published on November 14 in JAMA Opthalmology.

The authors reported no competing interests.

Review Date: 
November 14, 2013